Recovery of ilmenite by a two-stage flotation process



Oct. 30, 1945.

R. A. PICKENS 2,387,856

RECOVERY OF ILMENITE BY TWO STAGE FLOTATION PROCESSES FPGTHFA? -FiledMay 26, 1942 2 Sheets-Sheet 1 CFI/.57459 ORE' R. A. PlKr-:Ns 2,387,856

Oct. 30, 1945.

RECOVERY OF ILMENITE BY TWO lSTAGE FLOTATION PROCESSES 2 Sheets-Sheetl 2Filed May 26. 1942 Cil/JHK@ OAE PPOOl/C o ffl'fZ/'Mf/VT I Arran/wry.

Patented ct. 30, 1945 RECOVERY oF ILMENITE BY A TWosTAGE FLOTATIONPROCESS Roy Alderson Pickens, Stamford, Conn., assgnor to AmericanCyanamid Company, New York, N. Y., a corporation of Maine ApplicationMay 26, 1942, Serial No. 444,500.

3 Claims.

This invention relates to froth flotation of ores particularly to thebeneiiciation of ilmenite ores by a two stage flotation process. l

In commercial practice the use of titanium has become more and moreimportant and accord,- ingly the demand for a high grade ore from whichit may be recovered has steadily increased. To carry out a satisfactoryrecovery it' is necessary to have an ore or a concentrate containing `atleast`50% of a titanium bearing mineral such as ilmenite, rutile and thelike. While there are many deposits of titanium ores States, the gradein most .cases is not sufficiently high to make the recovery of titaniumeconomi cally feasible. As a consequence, in the past a large proportionof the titanium used was obtained from imported ores.

In order to make use of the domestic ores, it has been proposed notationto produce grade for further processing.r been madeto float the ilmeniteimpurities by the use of anionic a concentrate of satisfactory Attemptshave away from the reagents such as oleic acid, sodium oleate, tailoel,talloel soap,

iish oil, fatty acids. anionic-type wetting agents and the like. It wasfound, however, that successful concentrationv to the desired graderequired an initial ore of fairly high grade'and extremely carefulcontrol of both the amount of reagent used and the flotation conditions.If any of these factors were allowed to'vary from rather exactingrequirements an unsatisfactory separation was obtained. As a result, theanionic notation was neither particularly useful nor desirableon acommercial scale furthe beneciation of many naturally-occurring ores.

Attempts have also been made to oatthe impurities such as talc,chl-orite and other silicate-` bearing materials which usually comprisethe -undesirable portions 'of low grade 'native ores away from theilmenite by the use of a cationic reagent. When using a cationic-type ofreagent alone it was foundthat with fairly high grade ore as the initialstarting material a satisfactory concentration could be obtained,although often at the expense of good recovery. However, the concentrateso produced was in a wholly unsatisfactory physical condition since itcould be neither readily ltered nor dried without resorting to equipmentand a degree of care in their use which would render the processcommercially undesirable.

Most of the lower grade ilmenite ores which require beneficiation inorder to produce a marketable product, fall within one of three classes.

to beneficiate them by froth:

in the United The rst of these comprises those ores of a sumciently highinitial grade so that a marketable grade can loe-obtained in a singlestep dotation either by floating the silicate-bearing materials awayfrom the'ilmenite ores or alternatively iloatl ing the ilmenite awayfrom the gangue with an anionic reagent. The present invention is notconcernedwith cresci' this high an initial grade.

The second of these classes comprises those part of the linished productores which permit a to be produced as tailings from a rougher silicateflotation and the remainder must be obtained by a retreatment of therougher silicate concentrate. Ores of this type will be referred to inthe succeeding portions of the present specication as easily-beneciatedores.

The third of these classes comprises those ores which in order toproduce a marketable grade require further treatment of both the roughersilicate tail and the rougher silicate concentrate. Ores of this typewill be referred to throughout the specification as dilicultlybeneiiciated ores.

According to the present invention it is possible to produceconcentrates which are of satisfactorily high grade with a good recoveryand also have the concentrate in suchI physical condition that it can bereadily ltered and dried. This is accomplished in general by the use'ofa two-stage flotation process in which a portion of the silicates andsilica are removed by iiotation with a cationic type of reagent afterwhich lthe ilmenite is concentrated by flotation with an anionic type ofreagent.

The invention is most readily set forth in connection with theaccompanying drawings in which: l

Figure 1 is a iiow sheet showing the procedure used with an ore which lsrelatively free from dicultly-separable, undesirable portions; and

Figure'2 is a ow sheet of the -procedure used with an ore containing afairly large amount of impurities which can be removed only with greatdiiiculty.

In connection with both Figures 1 and 2, it may*i be noted that thepresent process is considered Also in both figures it win be noted thatthe f first otation stage is a silicate rougher `lieta-- tion using acationic reagent. Since the, cationic reagents are extremely sensitiveto the presence of slimes, even small amounts of the latter seriouslyimpairing the efficiency of the reagent, it is necessary to removeas'large a proportion of the slimes as practicable before this firstflotation step. If desired, a preliminary desliming may be carried outon thel ore after it has been crushed and before ne grinding although itis unnecessary to do so in all cases.

In preparing the ore for desliming, a procedurewhich produces goodresults is to wet grind the previously crushed ore with a sufficientamount of an alkaline material such as caustic soda or soda ash tomaintain the liquid in the grinding apparatus at a basic pH. Thegrinding may be carried out in any desired form of apparatus. Goodresults may be obtained using almostany commercial form of rod or ballmill. In some instances I have found that it is desirable to grind thematerial until about 1% is retained on a 65 mesh screen and 48-50% willpass a 200, mesh screen, although the process need not be limited tothis degree of grinding. Excessive grinding should be avoided since ittends to increase the amount of titanium mineral removed with the slimesand thereby lost.

The ground ore is then subjected to a desliming procedure. Again thetype of apparatus used is immaterial and the operation may be carriedout for example either by hydraulic classification or by means of aseries of wet screens. Hy-

draulic classification is probably the quickest and easiest means andtherefore, is perhaps preferable. The desliming, as was set forth above,should be carried out to the greatest extent that is feasible under theexisting conditions since the l morer complete Ythe deslirning the moreefiicient will be the action of the cationic reagent used in the rstflotation step.

After desliming, as will be noted in both Figures 1 and 2, the sands arepassed to a flotation machine or a battery of notation machines whichmay be of any desired type such as the well known Fagergren flotationmachine. In some cases it has been found advisable in connection withthe silicate' rougher flotation to condition the pulp for a few secondsbefore adding the reagents, in this case a frother and a promoter of thecationic type. g

An advantage ofthe present invention is that neither stage is, limitedto any particular re-v agents. any desired frothers and any desiredcationic or `anionic type promoters being satisfac-y tory in the firstand second stages respectively. For example, well-known frothers such aspine oil, cresylic acids and a mixture of higher alcohols known to thetrade as i3-23," comprising principally C1 and Ce, have been found to'produce excellent results. In the first stage,.any desired cationic typeof flotation reagent such 'for example as the quaternary ammoniumreagents, th higher aliphatic amines or their salts` and the reactionproducts of polyamines with higher aliphatic carboxylic acids may beused. All produce ysatisfactory 4results when used according to theprocess of the present invention.

With different ores, different cationic reagents may showslightly-superior results. However, it is an advantage of the presentinvention that this factor need not be considered. If only the cationicfloat were to be used, great care would necessarily be employed inselecting the optimum amounts of the best agent. But since this is nottrue of the present process in which the cationic `whole ilmenitenotation notation is in effect a preliminary treatment, this degree ofcare is not necessary. Any available reagent may be used so that thecheapest is the most preferable. At the Sametime, the minimum amount ofreagent may be used. Since these reagents are fairly expensive, thisfeature of the invention is of considerable importance.

Referring to Figure 1, delineating the procedure suitable for easilyconcentrated ores, the silicate concentrate from the silicate rougherfiotation is subjected to a cleaning flotation and if so desired to oneor more recleaner silicate ilotation operations. Since the cleanedsilicate concentrates 'are usually relatively free from ilmenite, theymay usually be 'discarded without appreciable loss. However, it ispossible to recover at least a portion of any ilmenite retained in therecleaned silicate concentrate by regrinding and reclassifying it,discarding the overflow and returning the underflow to the silicaterough'- er flotation stage.

The tailings from the silicate rougher flotation with easilybeneilciated ores of this type are usually of suiliciently high grade toconstitute a finished product. With some few'ores the tailings from thesilicate cleaner flotation may also be added directly tothe silicaterougher tail without causing the latter to fall below the desired grade.However, as previously pointed out, the present invention is notconcerned with ores of that high an initial grade since thereby the isby-passed and the process of the present invention is not required inthe beneilciation of such ores.

With ores of the type with which the present invention is concerned,however, the tailings from the several silicate cleaner notations arecombined-and subjected to an ilmenite rougher flotation with a flotationreagent of the anionic type. Again the particular reagent used is notcritical. Good `results may be obtained using such wellknown reagentsfor example, as oleic acid, coconut oil fatty acid, talloel, saponiedfatty acids and saponied talloel, although the invention is not meant tobe limited to these particular reagents since others ofa similar naturemay be used. The tailings from the ilmenite rougher flotation itself maybe discarded or if the ilmenite content is high enough to warrantfurther treatment, this material may be retreated by any of theconcentrate is passed to one or more cleaning stages the nnalconcentrate from which is the finished product andthe tailings fromwhich may be discarded or may/ be combined and retreated by methodssimilar to that previously described for the treatment .of the roughertailings. By this two-stage flotation procedure ores which otherwisecould not be beneciated may be successfully used and ores' `of greatlyvarying grades may be fed to this process and still produce a product ofsatisfactory grade with a good recovery.

A further advantage with the two-stage notation procedure lies inthefact that although in the case of easily treated 'ores only the initialsilicate flotation step maybe necessary in order tion may not be inparticularly good physical` state for subsequent dewatering and drying.IIn such cases it may be advisable to reiloat this .portion along withthe 'tailings from the silicate cleaner and recleaner stages in order totake advantage of the improvement in physical state made by the anionicotation.

This procedure will be illustrated by the following example which ismeant to be merely illustrative and in no way limit the presentinvention. All parts are by weight.

EXAMPLE 1 1200 parts of a North Carolina ilrnenite ore were crushed topass a mesh screen, diluted to about 67% solids, ground in a small rodmill for 13 minutes with 1.25 lbs/ton of caustic soda and then deslimedby decantation. The deslimed sands were diluted to 33% solids,conditioned for about l0 seconds with 0.1251b./ton of pine oil and 0.125lb./ton of llioroly amine hydrochloride, a commercial product comprisingprincipally lauryl amine hydrochloride and well-known to the trade as D.P.-243, and oated for 2 minutes in a Fagergren iiotation machine. Theconcentrate was given a cleaning and a recleaning oat of 2"minutes eachwith 0.02 lb./ton of Lorol aminehydrochloride. The rougher silicate tailwas a iinished product and was not further treated. The cleaner andrecleaner silicate tails were combined, diluted to .30 seconds with 0.12lb./ton of oleic acid and floated for 4 minutes with l0.07 lb./ton ofadditional oleic acid. The ilrnenite rougher concentrate was given acleaning and recleaning float of 2 minutes each, without reagents, andan addi tional recleaner float with 0.03 1b./ton of oleic acid. Theresults are shown in Table I;

Table I .d Assay f erccntA rt percent dist. T102 IiOz Feed 100. 00 42.20 100. 00 slime (waste) 24. 43 22. 43 12. 9s- Sand (flotation feed).75. 57 48. 59 87. 02 silicate rougher conc 52. 39 45.87 56. 94 silicaterougher tail 23. 18 54. 76 30.08 silicate recleaner conc. (waste) 7. 3819. 75 3. 46 Combined silicate cleaner tails (ilrnenite rougher feed)45. 0l 50. 15 53. 48 Ilmenite rougher conc. 39.81 52. 80 49. 80 Ilmemterougher tail.. 5. 20 29. 87 3. 68 Ilmenite recleaner conc 33. 53. 9742.65 Ilmenite recleaner tail (middlings) 6.46 46. 74 7. 15

Product combinations Silicate rougher taiH-ilmen ite recleaner conc 56.53 54. 29 72. 73 Silicate rougher tail-i-ilmenite recleaneroonc.+iln1enite middlings- 62. 99 53. 52 79. 88

Figure 2 is a ow sheet which represents the procedure with an ore whichcontains a large proportion oi diftlcultly removable impurities such asweathered chlorite and certain forms of iron bearing minerals. The oreis prepared in the same way, by grinding and desliming and the sameflotation reagents'are used as in the procedure outlined in Figure 1.With these diflicultly beneciated ores, the principal changes inprocedure lie in the manner in which various concentrates are combinedto make up the product and in the mannerf in which various tailings maybe reworked. The silicate rougher concenL solids, conditioned for about3 the rougher silicate oat instead of being a nished product arecombined with the tailings from the recleaner stages and subjected to arougher ilrnenite flotation with an anionic type of reagent. Thetailings from the rougher ilrnenite oat are usually fairly high intitanium content and consequently may advantageously be retreated,although if the .titanium content is low they may be discarded. `Theilrnenite rougher concentrate lmay be of suiliciently high grade to beiinished product, although ores in which this is possible are seldomencountered. It is usually advantageous to subject the ilrnenite rougherconcentrate to one or more cleaning stages, the concentrate from the nalstage of which forms the product. The combined tailings from the cleanerstages should ordinarily be recycled to the rougher ilrnenite oat torecover` part of their titanium content. However, if the tailingscomprise a large amount of fine titanium ore ties, it may be well toregrind these tailings prior to further treatment.

This modification of the procedure will be illustrated by the followingexamples which are also .I meant to be merely illustrative and not byway of limitation. All parts are by weight.

EXAMPLE 2 l l -chlorethyloleate, a cationic type reagent. The

trate is passed to a cleaner silicate flotation and the concentratetherefrom subjected to one or silicate rougher concentrate was given acleaning and recleaning iioat of 3 minutes each and the recleanedsilicate concentrate discarded. The silicate rougher tail wascombinedwith the tailings -from the cleaner and recleaner floats,diluted to about 30% solids, conditioned for 45 sec-` onds and oated for2'1/2 minutes with 0.12 lb./ton oleic acid. The ilmenite once. Themetallurgical results vare shown in Table II.

Table "II Assay Per cent Per gent per cent dist. W i0. Tio,

F ced 100. 00 43. 47 100. 00 Slime (waste) 20, 36 2l. 42 20. 04 Sand(flotation fee 79. 64 49.11 89. 96 Silicate reclean. conc 2.67 28. 25 1.73 Silicate rough. teil4-combined silicate clean. tails (ilrneniterougher v feed) 76. 97' 49. 83 88. 23 l'lmenite rough. tail.. 13. 39 39.07 l2. 03 Ilmenlte clean. taiL.- 7. 23 46. 24 7. 69

Product I lmenite clean. conc 56. 35 52. S5 68. 51

EXAMPLE 3 ing 0.06` lb./ton of B-23 and 0.08 lb.`/ton of anA aliphaticamine hydrochloride, principally octadecyl amine and known tothe tradeas Armour amine hydrochloride, in the cationic float and 0.7 lb./ton ofoleic acid inthe anionic float. The

cleaner and recleaner silicate tails, however, were physically bound toimpuri-v soda, ground in a rod mill for.

concentrate was cleaned not combined' with therougher silicate tail fromthe anionic oat but were discarded since they contained negligiblequantities of titanium. The results are shown in Table 1212i.v

Table III 5 Assay Per een rekent per cent d T100 T10;

eed. 100. 00 43. 39 100.00 Slime (white) 2). 12 21. 64 10. 03 79. 88 4B.S7 8. W Silicate rough. conc 6. 13 14. 44 1. 71 Bilicate rough. tail(ilmenite rough.

leed) 74. 76 51.21 88. 26 Ilmenite rough. tail. 211.30 44. 42 m. 78Ilmenite c1ean.'tail.. 5. 92 48. 29 0. 69

Product L Ilmenite clean. conc 48. 53 64. 44

Exmtn 4 20 The procedure of Example 3 was repeated using 0.06 lb./ton ofpine oil and 0.10 lb./ton of Lorol amine hydrochloride in the cationicfloat and 1.0 lb./ton ofsaponifled talloel in the anionic float. Theresults are shown in Table IV.

Table IV Assay Per cent Per cent per cent st. Wt- Tio. 110, 3

Feed 100. 00 41. 70 100.00 Slime (waste) 20. 38 20. 42 9. 96 Sand(flotation feed) 79. 6g 47. 26 v 90.04 Silicete clean. conc. 14. l 29.61 9. 99 S1l1catc comb tai 35 tion feed) 65. 52 51. 06 80. 05 Ilmeniterough. tail .v 5.81 34. 17 f 4. 75 Ilmenite clean. tail 3. 8l 50. 57-4.61

Product A Ilmenite clean. conc 55.90 52.85 70.69 4() l EXAMPLE 5 Table V50 Assay Percent Pevent percent dist. T10; T102 Feed 100.00 42. 100.0055 d) 75. 35 49. 12 87. 41 Ilmenitc rough. tail 27. 57 46.93 30. 56Ilmenitc clean. tail 5. 67 45. 6. 10 60 Product Ilmenite clean. conc.42.11 51. 05 50. 75

EXAHPL: 6 -The procedure of Example 3 was repeated usine 0.35 lb./ton oftrimethylcetyl ammonium bromide in the cationic float and 0.3 1b./ton ofoleic acid in the anionic float. 'I'he results are shown in Table VI.

Table VI Asse Percent Rgent percent dist.

- T10, 'riosl 100.00 43.13 100.00 .ms @.42 L35 70. 02 4am 0.00 I 3.0230.15 A 2.15 70.00 40. 00 sa 20 13.10 41.00 12. 51 Ilmenite clean. t0ns. sa 40. 0c 9. s4

Produc: 110100110 010010.00110 54.00 5210 eene I claim: 1. Aprocess ofbeneflciating low grade ilmenite ores to produce a beneciated oreadapted to ready filtration and drying and assaying at least 50% T10:which comprises subjecting the ore to a lrougher silicate flotation inthe presence of an amount of a cationic-type collector effective toconcentrate a major portion of the silicates but insufilcient to effecta maximum separation, whereby a concentrate rich in silicates and a tailrich in ilmenite are obtained, subjecting the rougher silicateconcentrate to at least one silica cleaner notation and subjecting atleast a part of the silicatevcleaner tailing to a rougher ilmeniteflotation in the presence of .an anionic collector selected from thegroup consisting of the higher fatty acids, talloel and soaps thereof.

2. A method according to claim l in which the silicate rougher`flotation tailing and the silica cleaner tailing are, combined as feedto the ilmenite rougher flotation.

3. A process of beneiiciating low grade ilmenitc ores to produce abeneciated ore adapted to ready illtration and drying and assaying atleast 50% TiOz which comprises grinding the lmenite ore in the presenceof an alkaline material to a size suitable for froth flotation feed,desliming the ground 'ore in the presence of water, subject ing thedeslimed ore to a rougher silicate flotation in the presence of anamount of a. cationictype collector effective to concentrate a majorportion of the silicates but insuiiicient to eect a maximum separation,whereby a concentrate rich in silicates and a tail rich in ilmenite areobtained, subjecting the rougher silicate concentrate to at least onesilica cleaner flotation and

